Desperately ill and seeking a miracle, David Bennett Sr. took the last bet on Jan. 7. when be became the first human to be successfully transplanted with the heart of a pig. "It creates the beat; it creates the pressure; it is his heart, " declared Bartley Griffith, director of the surgical team that performed the operation at the University of Maryland Medical Center.
Bennett, 57, held on through 60 tomorrows, far longer than any previous patient who'd received a heart from another species. His remarkable run offered new hope that such procedures, known as xenotransplantation（异 种移植）, could help relieve the shortage of replacement organs, saving thousands of lives each year.
The earliest attempts at xenotransplantation of organs, involving kidneys from rabbits, goats, and other animals, occurred in the early 20th century, decades before the first successful human-to-human transplants. Rejection, which occurs when the recipient's body system recognizes the donor organ as a foreign object and attacks it, followed within hours or days. Results improved after some special drugs arrived in the 1960s, but most recipients still died after a few weeks. The record for a heart xenotransplant was set in 1983, when an infant named Baby Fae survived for 20 days with an organ from a baboon（狒狒）.
In recent years, however, advances in gene editing have opened a new possibility: re-edit some genes in animals to provide user-friendly spare parts. Pigs could be ideal for this purpose, because they're easy to raise and reach adult human size in months. Some biotech companies. including Revivicor, are investing heavily in the field. The donor pig was offered by Revivicor from a line of animals in which 10 genes had been re-edited to improve the heart's condition. Beyond that, the pig was raised in isolation and tested regularly for viruses that could infect humans or damage the organ itself.
This medical breakthrough provided an alternative for the 20% of patients on the heart transplant waiting list who die while waiting or become too sick to be a good candidate.
